This invention relates to hoists and in particular to motor vehicle hoists which are portable and mobile allowing an operator to manually move and manipulate an elevated motor vehicle.
The motor vehicle industry, particularly that part of the industry involved in maintenance, repair and renovation, has a constant demand for aids to assist in the manipulation and handling of vehicle bodies which cannot be handled confidently without mechanical assistance.
Such aids include lifting devices, mounting devices and holding devices of various descriptions. Lifting devices range from simple one point jacks which lift a single point on a vehicle to massive inground fixed hoists which raise the entire vehicle to allow clear standing access underneath.
Mounting devices include simple axle stands and ramps to complex jigs capable of rotating a vehicle from a horizontal to a vertical orientation.
Whilst all the previously mentioned devices have clear application and use in the industry, one of the more frequent requirements in the industry is to easily manipulate and move a vehicle which may have no wheels, damaged suspension, no engine etc; or move a collection of vehicles in a confined space, or simply raise an entire vehicle half a meter or so where it stands to allow clear access underneath.
To date, none of the available devices cater for the above range of handling requirements. Workshop situations often find vehicles precariously placed on four individual axle stands or suspended on trolley jacks. Inground hoists also present limitations as vehicles are fixed at one place in a workshop until they are mobile of their own componentry and the hoist is unavailable for other uses. Inground hoists are also highly expensive installations.
Other solutions are available including placing vehicles on elevated trolleys of a fixed height; however, such devices require the elevation of the vehicle to the trolley height and do not provide a complete solution to the above-described problem.
One object of the invention is to provide an improved vehicle hoist which is compact and capable of raising and readily moving a vehicle without further mechanical assistance with one operator.
In one aspect, the invention provides A hoist for a vehicle including a lower chassis adapted for secure placement on and optional general movement about a floor, an upper platform fitted to said chassis and movable between a first lowered position to a second raised position wherein said hoist is capable of placement underneath a vehicle when in said first position and said platform and chassis remain coplanar during movement between said first and second positions and both said platform and said chassis have a footprint sufficient to allow stable holding of a vehicle when mounted on said hoist characterised in that said hoist is fitted with a locking means for holding said upper platform in said raised position said locking means including an elongate locking arm pivotally fitted to one end of said chassis and telescopically passing through a collar pivotally fitted to the other corresponding end of said platform wherein said collar has a lock adapted to co-operate with said locking arm to arrest said telescopic movement and lock said hoist.
The lock preferably incorporates a pawl fitted to the pivoted collar which may be spring loaded and bias to intercept the travel path of the locking arm as it passes through the collar. The locking arm may be provided with a plurality of protuberances or indentations along its length which are adapted to co-operate with the pawl to arrest any backward movement of the locking arm and hoist.
The pawl preferably acts through a pivot positioned to allow the pawl to engage the locking arm by an over center motion thereby ensuring that once the pawl has engaged a step or indention in the locking arm, it is only possible to release the pawl if the locking arm has moved forward so as to allow the pawl sufficient space to again move over center and withdraw thereby releasing the lock. The hoist may also include wheel means to provide mobility to the hoist if required. The wheel means may be castor systems including a swivel housing fitted to the lower chassis which can sit on the floor when the wheels are retracted or optionally elevate the hoist by the raising of an arm pivoted intermediate on said housing where the arm has a wheel fitted at the other end.
The footprint of said hoist is preferably at least 20% of the mounted vehicles wheel footprint.
The hoist may have a substantially rectangular footprint in the lower chassis and upper platform with raising arms pivotally fitted in the region of the respective corners of said lower chassis and said upper platform so as to allow said upper platform to be raised and lowered relative to said chassis causing said platform to offset forward or rearward during said raising and lowering.
The hoist may be moved between said first and second positions by a ram fitted between a rearward position on said lower chassis and a forward position on said upper platform such that activation of said ram causes said upper platform to simultaneously move forward and up relative to said chassis.
The upper platform may be adapted to lay flat against said chassis when in said first position.
The raising arms may be of equal length and corresponding fitting to each corner region of the hoist The arms may be provided with steps to limit the raised position of the hoist to pre-overcentering of said raising arms.